Cooperative object tracking and event detection with wireless smart cameras

Wireless embedded smart cameras not only capture images, but also can perform processing and communication. However, many system- and algorithm-wise challenges remain to be addressed to have operational, battery-powered wireless smart-camera networks, since they have limited processing power, memory, energy and bandwidth. In this paper, we present a wireless, embedded smart camera system for cooperative object tracking and event detection, wherein each camera platform consists of a camera board and a wireless mote. Light-weight background subtraction and tracking algorithms are implemented and run on the camera boards. Cameras communicate in a peer-to-peer manner over wireless links to exchange data, and thus to consistently track objects. In a wireless smart camera system, transferring large amounts of data between cameras should be avoided, since it requires more power, and incurs more communication delay. In the presented system, cameras exchange small-size packets for communication. Also, with wireless smart cameras, it is not viable to transfer all the captured frames to a base station due to limited resources. Instead, we define events of interest beforehand, and embedded smart cameras save only those portions of the live video capture where the defined event scenario occurs. We present results of tracking and detecting objects entering a region of interest, all of which are performed on the microprocessor of camera boards. We also show examples of consistently tracking objects, moving across different camera views, by wireless data exchange.